Not necessarily. Encryption can be open source, and still be secure. I know how a safe works, but does that mean I can easily break into one? Encryption typically requires a key, or some variable to salt the hash (so the output changes). I can know the algorithm, but if I don't know all the information that was used to create the output, the data is still locked away. If I can cheat the system and get a key (as mentioned is how pretty much all known DRM removal apps work), then I can reverse the process. Otherwise, my only real option would be to brute force it, which is to basically guess what the key is, see if that produces an acceptable result, and try again if not.

As far as what the OP wants, probably won't find much. Most FLOSS guys are decidedly antiDRM, because it flies in the face of the spirit of open source (free and open sharing). On top of that, it would actually hinder sales, because then it would only work on devices that supported that particular DRM. For instance, if the OP publishes a book in a custom DRM method, it wouldn't be usable on really any ebook reader.